Stop motion protective circuit for rotary textile machine



Sept. 29, 1970 F. H. YARBRQUGH 3,530,689

STOP MOTION PROTECTIVE CIRCUIT FOR ROTARY TEXTILE MACHINE Filed March 12, 1968 To Termlnol (a) of Transformer 2| wP/zz ATTORNEYS.

United States Patent 3,530,689 STOP MOTION PROTECTIVE CIRCUIT FOR ROTARY TEXTILE MACHINE Fred Hall Yarbrough, Winston-Salem, N.C., assiguor t0 Hanes Corporation, Winston-Salem, N.C., a corporation of North Carolina Filed Mar. 12, 1968, Ser. No. 712,562 Int. Cl. D04b 35/10; G08b 21/00 US. Cl. 66-157 6 Claims ABSTRACT OF THE DISCLOSURE FIELD OF THE INVENTION The invention relates to electric stop motions, and particularly to stop motions employed in rotary knitting machines in which the cam mechanisms and yarn supplies rotate.

DESCRIPTION OF THE PRIOR ART Rotary knitting machines of the types indicated are conventionally equipped with several types of stop motion detectors, as, for example, stop motion thread detectors for detecting yarn breaks and yarn knots, and needle detectors for detecting lumps of foreign materials at the needle cylinder. Such stop motion detectors are associated with normally open electric switches which, in the case of the thread detectors, are held open under the control of the travelling yarn, and, in the case of the needle detectors, are held open by biasing means. In the event of a yarn break, or a yarn knot, or in the event of a lump of foreign material at the needle position, the stop motion detectors operate automatically to close the switch to complete an electric circuit to actuate the solenoid or electromagnetic device to release the energy stored in the spring of the loaded knock-off mechanism, to stop the knitting machine.

Since the stop motion detectors rotate with the machine, electric energy to the stop motion detectors of a rotating knitting machine is conventionally fed through a wiper contact to a slip ring which rotates with the machine. Where, as is frequently the case, a number of knitting machines are operating together in the same room, unwanted material such as lint, dirt, grease, etc., tends to settle on the slip ring and to accumulate at the wiper contact, thereby preventing good electrical contact between the wiper and the ring. In the conventional machine, the attendant is not provided with any sort of warning that the electrical contact at the wiper has been broken, or that the resistance at the wiper contact is so high that insufiicient current will flow. In such case, upon the breaking of a thread or the collection of foreign material at the needle position, and the resultant closing of a stop motion detector switch, the knitting machine will continue to run, and considerable damage may result, the correction or repair of which may be costly in both time and money.

The stop motion detector systems shown in the prior 3,530,689 Patented Sept. 29, 1970 art US. Pats. 2,387,100 and 2,625,027 are unprotected from the hazard discussedabove.

SUMMARY OF THE INVENTION One object of the present invention is to provide auxiliary means to stop the machine when no electrical energy is available at the stop motion detectors. Another object is to provide an auxiliary circuit which merely indicates whether or not electric energy is available at the stop motion detectors. The indicator means may be visual, such as a signal lamp, or may be audible, such as a bell or horn. The auxiliary circuit, whether relay stop motion or indicator, is energized from the same electric energy source as is used to energize the stop motion knockoff mechanism. Electric energy for the auxiliary circuit is taken from the rotating slip ring of the knitting machine by means of an auxiliary wiper contact. The current through the auxiliary circuit also flows through the winding of the electromagnetic device of the knock-off mechanism. To avoid tripping the knockoif mechanism prematurely, the current through the auxiliary circuit is controlled to a magnitude less than that required to actuate the electromagnetic device. If good electrical contact between the main wiper and the rotating slip ring is broken, due to the accumulation of lint, dirt, grease or other reason, current flow through the auxiliary circuit will be interrupted and the relay will close to stop the machine, or the signal lamp will be extinguished, or the horn will sound. Or, if the wiper-to-slip ring contact is not completely broken but, due to lint, etc., becomes a high resistance contact, insufficient current will flow to maintain the relay open or to maintain the signal lamp at its usual brightness. In either event, the attendant will have warning that power to the stop motion detector circuits has been cut off or seriously reduced.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an illustration of the relay stop motion embodiment, partly schematic partly diagrammatic; FIG. 2 illustrates the indicator embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Shown diagrammatically in FIG. 1 of the drawing is an electric motor 10 energized from a 230-volt power line L112. Motor 10 drives an output shaft 12 through a clutch 14. A brake 16 is provided for shaft 12 and applied when clutch 14 is disengaged. Shaft 12, through suitable known drive means, represented by the dot-anddash line 15, drives the rotary machine 100. Drive 15 is indicated as being connected to the center post 60 of the machine 100 but this is merely diagrammatic. In many cases, the machine is driven by a worm or pinion which engages a ring gear at or near the periphery of the machine.

In the description which follows, machine 100 will be assumed to be a rotary or circular knitting machine in which the cam mechanisms and yarn supplies rotate, but the machine could be some other form of rotating machine having stop motion detectors which need proof of the availability of electric energy.

Also shown diagrammatically in the drawing is a known form of stop motion knock-olf device or controller 70. Controller may, for example, be of the type disclosed in U.S. Pat. 2,285,237. The controller 70 is set, or cocked, or loaded, by pulling the handle 78 of rod 70 to the left to the position shown in the drawing. In this this position, the main compression spring 77 is compressed between the housing boss and spring retainer 76. When the controller 70 is in the set position, clutch 14 is engaged and brake 16 is released. After setting, controller 70 is maintained in the set or cocked position by a pawl or latch 75 which is biased toward latching position by a compression spring 72. Release of latch 75 is controlled by a solenoid or electromagnetic device 71, which is illustrated as having a core 74 the left smalldiameter portion of which is non-magnetic, such as brass, and the right larger-diameter portion of which is magnetic, such as steel. The left end of core 74 abuts against the biasing spring 72; the right end of the core 74 is connected pivotally to the latch 75, which is pivotal about point 69.

It is to be understood that the knock-off device or controller 70 shown in the drawing and described above is merely exemplary or representative of the construction and operation of a known form of controller. For details of the construction of such controllers, reference may be had to US. Pats. 2,285,237; 2,357,713; 2,490,- 936; 2,625,027, and others.

When sufficient current flows through the winding 73 to pull the magnetic end of core 74 inward, to the left as viewed in the drawing, the latch 75 is pivoted clockwise about point 69 and latch 75 releases the retainer or flange 76, thereby allowing the energy stored in main spring 77 to move rod 79 to the right. This disengages the clutch 14, and applies the brake 16 to the shaft 12. In this manner, the machine 100 is stopped.

As has already been indicated, the mechanism described thus far is merely illustrative of Well-known and conventional mechanisms.

The remainder of the drawing is largely a schematic representation of portions of a circular knitting machine 100 as viewed in plan view. Reference numeral 60 identifies the steel center post or pole, which is electrically grounded; 50 identifies a conventional steel ring which is grounded electrically, as by a connector 51 to the center pole 60; 40 identifies a conventional energized steel ring which is insulated from the grounded machine; 30 identifies a known form of steel slip ring which is insulated from the grounded machine and which is connected to ring 40 as by connector 31; and 33 identifies a steel ring which is grounded as by a connection 34 to the center pole. All of these members of the knitting machine, namely, rings 33, 30, 40, and 50, and center pole 60, rotate when the knitting machine is operating.

As has already been indicated, it is conventional in rotary knitting machines of the type being described, to provide stop motion detectors for detecting broken yarn ends and/or yarn knots. It is also conventional to provide stop motion detectors for detecting the accumulation of foreign material at the needles at the needle cylinder. A relatively large number of detectors of each type are used on each kniting machine. In the drawing, the thread detectors are represented schematically by the plurality of switches 42 shown connected between rings 40 and 50, and the needle detectors are represented by the plurality of switches 32 shown connected between rings 40 and 33. Since the stop motion detectors are associated with normally open switches, the switches 42 and 32 are shown in open position. In the case of the thread detectors 42, the switches are held open by the continuous thread. In the case of the needle detectors 32, the switches are held open by spring biasing means until triggered closed by a defect at the needle position.

When a thread or needle defect is detected, and the stop motion detector switch associated therewith closes, the closing of the switch completes an electrical circuit and triggers the electromagnetic device of knock-off or controller mechanism 70 to stop the machine. The electrical circuitry by which this is accomplished is well known in the art. A simplified example of such circuitry is illustrated schematically in the drawing and will be but briefly described.

In the drawing, a step-down transformer 20 is shown, the primary of which is connected across the line Ll-L2. Transformer 20 reduces the voltage to a suitably low voltage for non-hazardous operation of the stop motion detectors. In the drawing, the line voltage is assumed to be 230 volts A.C., stepped down by the transformer to 16 volts. One terminal a of the secondary 21 of transformer is connected, as by lead 22, to a wiper 23 which, unless prevented by the accumulation of lint, dirt, grease, etc., makes a good sliding or wiping contact with the rotating steel slip ring 30. The other terminal b of the secondary 21 is connected to one end of the winding 73 of the solenoid or electromagnetic device 71. The other end of the winding 73 is grounded at 81.

Slip ring is connected electrically by connector 31 to the steel ring 40. One terminal of each of the thread detectors 42 is connected to ring 40. The other terminal of each of the thread detectors 42 is connected to the ring which in the drawing is shown connected elec trically by connector 51 to the grounded center post or pole of the machine.

As has been previously indicated, when the knitting machine is operating, the slip ring 30, the distributor ring 40, the grounded rings 33 and 50, and the center pole 60, are all rotating, as are all of the thread detectors and all of the needle detectors. If, due to a broken thread, one of the thread detector switches 42 should close, an electric circuit will be completed and current will flow through the winding 73 of electromagnetic device 71 of sufiicient magnitude to pull core 74 to the left, thereby tripping the latch 75 and releasing the energy stored in main spring 77. Rod 79 will move to the right, the clutch 14 will be disengaged, and the brake 16 will be applied to stop the machine.

The electrical circuit through which current flows when a stop motion thread detector switch is closed may be traced from terminal a of secondary 21 of transformer 20 through conductor 22, wiper 23, slip ring 30, connector 31, ring 40, the closed thread detector switch 42, ring 50, connector 51, pole 60, ground 61, ground 81 at the device 70, winding 73 and back through conductor 24 to terminal 12 of the transformer secondary.

In similar manner, if a needle detector switch 32 should close (instead of a thread detector switch 42 as discussed above) the electrical circuit would be completed from terminal a of the transformer secondary 21 through conductor 22, wiper 23, slip ring 30, connector 31, ring 40, the closed needle detector switch 32, ring 33, connector 34, pole 60, ground at 61, ground at 81, winding 73, and back by way of conductor 24 to terminal b of the secondary winding. Again, sufficient current would flow through this circuit to actuate the electromagnetic device 71 and trigger the controller 70 to knock-off the machine.

If, at the time the thread detector switch 42, or the needle detector switch 32, closes, the wiper 23 is not in good electrical contact with the slip ring 30 due to the accumulation of lint, dirt, grease or other high resistance material therebetween, the closing of the detector switch will not effectively complete the electrical circuit and no current will flow through the coil 73 of the electromagnetic device 71, or, a very small quantity of current may flow, but too small in magnitude to actuate the electromagnetic device 71. In such case, particularly in the case of accumulated foreign material at the needles, a great deal of damage may be done before the condition is noticed by the attendant, since the attendant is, in most cases, attending to a number of machines.

It is to this problem that the present invention is directed. The invention provides an auxiliary circuit (FIG. 1) or 161 (FIG. 2) whose operation depends upon whether or not electrical energy is available to the regular stop motion detector circuits. In the preferred embodiment, illustrated in FIG. 1, the auxiliary circuit contains a relay 54 having a winding 55 and a pair of normallyclosed contacts 56 one of which is connected to ground at 57 and the other of which is connected by lead 58 to terminal a of the secondary 21 of transformer 20.

The auxiliary circuit 160, is connected to a second or auxiliary wiper 63 which under normal conditions makes good electrical sliding contact with the rotating slip ring 30. It will be seen that if the main wiper 23 and the auxiliary wiper 63 are both making good contact with slip ring 30, current will flow from the transformer secondary 21 through a closed electrical circuit which may be traced from the secondary terminal a through the conductor 22, main wiper 23, slip ring 30, auxiliary wiper 63, resistor 64, winding 55 to ground at 59, and then by way of ground connection 81, coil 73 of electromagnet 71, and lead 24 back to terminal b of the transformer secondary. Thus, the relay 54 will be energized and the normally-closed contacts 56 will be held open so long as both of the wipers 23 and 63 continue to make good electrical contact with the slip ring. This assumes, of course, that other components of the circuit are in good order. It assumes, for example, that there has been no failure at the transformer 20.

It will be observed that with the installation of the auxiliary relay circuit 160, current will flow under normal conditions through thewinding 73 of the electromagnetic device 71, even when no stop motion detector switch is closed. It is important, therefore, that the resistance values of the components of the auxiliary circuit 160 be so selected, that the current through the winding 73 resulting from the current flow through the auxiliary relay circuit 160 be insufficient to actuate the electromagnet 71. This is achieved by selecting a suitably high resistance winding 55 for relay 54, or by inserting a suitably high resistance 64 in series with the relay winding 55.

If, due to the accumulation of lint or dirt at wiper 23, the good electrical contact at 23 should be broken or be sufficiently impaired, the current flow through the winding of relay 54 will become insufiicient to maintain the relay energized and the contacts 56 will no longer be held open. Closing of the contacts 56 completes a circuit through winding 73 of the electromagnetic device 71 and sufficient current now flows to actuate the electromagnet 71, thereby stopping the machine. The circuit may be traced from terminal b of secondary 21 of transformer 20 through lead 24, winding 73 of electromagnet 71, ground at 81, ground at 57, the closed contacts 56 of relay 54 and back by way of lead 58 to terminal a of the secondary 21 of transformer 20.

While the arrangement shown in FIG. 1 (which is effective to stop the machine when no current (or insufficient current) is available to the regular stop motion detector circuits) is presently preferred, the arrangement shown in FIG. 2 has certain advantages, namely, it permits the attendant to correct the condition of accumulating lint at wiper 23 without stopping the machine.

In FIG. 2, the auxiliary circuit 161 contains an indicator lamp 65 instead of the relay 54. Here again, a series resistor 164 is included of sufficiently high resistance so that the current which flows through winding 73 of electromagnet 71 due to current flow through the auxiliary lamp circuit 161 when no stop motion detector switch is closed will be insutficient .to actuate the electromagnet 71.

It will be seen that the lamp 65 will be illuminated at substantially its full brilliance so long as both of the wipers 23 and 63 continue to make good electrical contact with the slip ring. This assumes, of course, that other components of the circuit are in good order. It assumes there has been no failure at the transformer 20, that the lamp filament is in good order, etc.

If the lamp 65 should go out, or, if the brilliance of the lamp should be materially lessened, its failure, or its reduced brilliance, will be noticed by the attendant, perhaps not immediately but within a short time, and, at least in most cases, before the closing of any of the stop motion detector switches. The attendant will thereupon investigate the conditions of the contacts at the wipers 23 and 63, and if either or both of these wipers is not 6 making good contact with the slip ring 30, the attendant will correct the condition, in many cases without stopping the running of the machine.

While the auxiliary circuit 161 of FIG. 2 has been illustrated and described as having a light bulb as the signal indicating means, other signal means may be used. For example, the current flowing normally through the auxiliary circuit 161 could be used to hold a relay in energized condition so that upon current failure, or upon a substantial decrease in current flow, the relay contacts would move to a normally-closed condition to close another electr'ical circuit to operate a buzzer or other audible signal device.

While the preferred embodiments of this invention have been described in some detail, it will be obvious to one skilled in the art that various modifications may be made without departing from the invention as hereinafter claimed.

What is claimed is:

1. A rotary textile machine having:

(a) drive means for driving said machine rotationally;

(b) disconnect means for disconnecting said machine from said drive means;

(c) electromagnetic means for controlling said disconnect means;

((1) means grounding said machine electrically;

(e) a conductive ring insulated from said grounded machine and adapted to rotate with said machine;

(f) stop motion detector switch means connected electrically between said conductive ring and the grounded machine;

(g) said detector switch means being adapted to rotate with said machine and being normally-open lbut adapted to be closed when an abnormal condition is detected;

(h) electrical energy supply means having first and second terminals;

(i) main wiper means for connecting said first terminal of said electrical energy supply means to said conductive ring;

(j) means connecting said second terminal of said electrical energy supply means to one terminal of said electromagnetic means;

(k) means connecting the other terminal of said electromagnetic means to electrical ground;

(1) auxiliary circuit means for sensing the availability of electrical energy at said conductive ring;

(111) second wiper means for connecting said auxiliary circuit means between said conductive ring and electrical ground,

(11) said auxiliary circuit means having such sufficiently high resistance as to draw insufficient current to actuate said electromagnetic means.

2. Apparatus according to claim 1 characterized in that said auxiliary circuit means comprises:

(a) a relay having a winding circuit and normallyclosed contacts,

(b) said winding circuit being connected between said second wiper means and electrical ground and hav- 1ng such sufficiently high resistance that the current flow when said stop motion detector switch means are open is insufficient to actuate said electromagnetic means but is sufiicient to maintain said normallyclosed relay contacts open,

(c) said normally-closed relay contacts being connected in circuit between electrical ground and said first terminal of said electrical energy supply means.

3. Apparatus according to claim 1 characterized in that said auxiliary circuit means comprises:

(a) a signal lamp and a resistor connected in series between said second wiper means and electrical ground.

4. In a rotary knitting machine having normally-open stop motion detector switches adapted to be closed upon detection of an abnormal condition to close an electrical clrcuit through an electromagnetic device to actuate the same to stop the machine, and in which electrical energy is supplied to said electrical circuit through a slip ring and a first wiper normally in electrical contact therewith, the improvement which comprises the provision of an auxiliary circuit to indicate the availability of electrical energy to said normally-open stop motion detector switches, said auxiliary circuit comprising:

(a) a second wiper normally in electrical contact with said slip ring;

(b) electrical energy indicator means connected between said second wiper and said electromagnetic device to provide for current flow in series therethrough;

(c) said electrical energy indicator means having a resistance value sufiiciently high to maintain said series current at a value insufiicient to actuate said electromagnetic device when said stop motion switches are open.

5. Apparatus according to claim 4 characterized in that said electrical energy indicator means comprises:

(a) a relay having a winding circuit connected between said second wiper and said electromagnetic device,

(b) said relay having normally-closed contacts connected between the source of electrical energy and said electromagnetic device,

References Cited UNITED STATES PATENTS 2,700,881 2/1955 Wachsman 66-163 2,880,381 3/1959 Antonevich 66-163 X 3,343,158 9/1967 Tellerman 340-419 3,379,037 4/ 1968 Antonevich 66-163 3,390,751 7/1968 Rogerson et a1. 66-163 X ALVIN H. WARING, Primary Examiner D. L. TRAFTON, Assistant Examiner US. Cl. X.R. 

